The present invention relates to the packaging of an integrated circuit assembly and, more particularly, to a heat sink and package lid arrangement for an integrated circuit package.
Package lids and heat sinks are generally used in integrated circuit assemblies. One such integrated circuit assembly is shown in FIG. 1. In FIG. 1, there is a system board 10 to which an integrated circuit package 12 is mounted. The integrated circuit package 12 includes an integrated circuit die 14. A package lid 16 (or heat spreader) is adhered to an upper surface of the package 12 to protect the integrated circuit die 14 and to act as an electromagnetic interference shield. The package lid 16 often serves to spread the heat generated by the integrated circuit die 14 over a larger area. Mounted to the package lid 16 is a heat sink 18, which is thermally coupled to the package lid 16 and serves to dissipate heat. In many conventional integrated circuit assemblies, the heat sink 18 is mounted to the lid 16 by a systems manufacturer.
As shown in FIG. 1, the system board 10 is equipped with an electrically conductive ground lead 20 and at least one more electrically conductive lead 22, which includes a connection to a power supply (not shown). In one conventional system, the ground lead 20 is electrically coupled to a conductive surface on the package 12 with an electrically conductive wire 24 or the like. Another electrically conductive lead 26 also extends from the system board to the electrically conductive surface on the package 12.
Alternatively, the heat sink 18 itself may be grounded to the system board 10 with an electrically conductive wire or the like. With this alternative, as shown in FIG. 1, a wire travels from the heat sink to the system board. As noted above, heat sinks are placed on the package lid by a systems manufacturer who may obtain heat sinks from a variety of different manufacturers. The heat sinks produced by varying manufactures may have differing sizes and shapes. As a result, system boards must have different sockets so that the different sized and shaped heat sinks can be grounded.
There are problems, however, with conventional integrated circuit package assemblies. One such problem is that, because heat sinks are normally placed on the package lid after the manufacturer of the integrated circuit package assembly has delivered the package assembly to the system manufacturer, different system board socket positions are needed for different heat sinks due to differing sizes and shapes. Another problem involves the need to ground the heat sink to the system ground, which involves wiring the heat sink to the system ground after the system board has been manufactured, thereby adding an additional step in the manufacturing process. Also, the connectors that connect the heat sink to the system ground are exposed, which can lead to breakage.
There is a need for a heat sink and package lid assembly that improves the assembly of the heat sink and package lid and reduces the risk of breakage.
These and other needs are met by embodiments of the present invention which provides an integrated circuit package assembly having a package board, an electrically grounded package lid mounted to the package board, and a heat sink mounted to the package lid and grounded only through the package lid.
The grounding of a package lid and mounting of a heat sink to the grounded package lid so as to ground the heat sink only through the package lid reduces the possibility of breakage as there are no exposed wires connecting the heat sink and the system board. Also, assembly is improved as the unit is more readily connectable to a system board. Moreover, the inventive heat sink-package lid assembly provides for a modular assembly that reduces manufacturing costs and reduces the number of parts.
Additional advantages and novel features of the invention will be set forth in part in the description which follows, and in part will become apparent to those skilled in the art upon examination of the following or may be learned by practice of the invention. The advantages of the invention may be realized and attained by means of the instrumentalities and combinations particularly pointed out in the appended claims.